The invention relates to a process and a system for controlling an electrohydraulic pressure supply for an auxiliary power device of an automotive vehicle for operating a hydraulic pump system by means of an electric motor, and wherein the electric motor is switched from stand-by operation to full-load operation only in case of need.
It is well known in automobile engineering to develop auxiliary power systems by means of external hydraulic energy. In such a case, a pump system is drive by means of an electric motor. The electric motor is connected directly to the battery voltage of the vehicle.
A change in load causes an increase in output, particularly an increase in current, of the electric motor. Power-assisted steering systems are known, for instance, which, proceeding from a stand-by operation, operate the electric motor with full power only in case of need. In his case, there is a difficulty of recognizing the case of need. Furthermore, full energy is fed to the system also upon operation under partial load. In addition, due to the finite rate of acceleration of the electric motor, there is a time delay in the response of the system which is disturbing to the driver.